This invention relates to an insulating tie strap for use in a load center, and, more particularly, this invention relates to a tie strap for identifying and structurally supporting the ground bars and neutral bars in load centers wherein the ground bar must be electrically isolated from the neutral bar in the load center.
In many building complexes, such as multiunit apartments, electrical power is directed into the complex through a main entrance from which the power is distributed to one or more remote load centers. Many, if not all, local electrical codes require that the neutral conductors and ground conductors be electrically connected at the entrance. These codes also require that the neutral conductors and ground conductors be electrically isolated beyond the main entrance at remote load centers.
In FIG. 1 a load center 1 used as a remote load center for housing circuit breakers 7 is illustrated. Both the right and left bars are neutral bars 2 which are electrically isolated from the metal load center enclosure 3. An aluminum tie strap 4 is normally connected between the neutral bars 2 to fix the neutral bars 2 in place and electrically connect the neutral bars. Without the aluminum tie strap 4 the neutral bars 2 are allowed to move relative to the metal load center enclosure 3. In a load center it is important to keep all electrical connections fixed in place securely so that the effects of heating and magnetic fields in the load center do not cause the connnections to move and losen. The losening of a connection will very frequently cause an increase in resistance at the connection and, accordingly, will cause unwanted heating at the connection. In an extreme situation the electrical connection can come apart.
To wire the load center illustrated in FIG. 1 as a remote load center in accordance with most codes, an electrician must obtain at least one separate ground bar 5 which is relatively costly. The ground bar 5 serves as a means for connecting the ground conductors at a remote load center while also ensuring that the ground bar 5 and conductors are electrically isolated from the neutral bars 2 and conductors.
One problem recognized with the above-mentioned wiring configuration is that many electricians do not wire the remote load centers according to this configuration. Many electricians avoid obtaining and using a separate ground bar 5 by removing the aluminum tie strap 4 and using one neutral bar 2 as a ground bar and the other neutral bar 2 as a neutral bar. This configuration provides for a ground bar and neutral bar electrically isolated from each other, but it does not provide means for fixing the ground bar and neutral bar into the load center. Accordingly, this configuration is prohibited by most codes and, if noticed by an electrical inspector, will require modification such that the aluminum tie strap is replaced and a separate ground bar is used. If this prohibited configuration is not noticed, a remote load center will exist wherein the ground and neutral bars are not fixed securely in place. Additionally, the ground and neutral bars will not be identified clearly.